核桃壳活性炭的制备及其对水中典型有机污染物的吸附研究

发布时间：2018-11-01 17:00

【摘要】：废弃生物质在废水处理的开发应用中有着环境、社会和经济的效益。本文选用核桃壳为原料,采用草酸铵活化改性-马弗炉加热炭化的方法法制备活性炭(CAC),产炭率为44.1%。用等电点、SEM、FT-IR、比表面积测定、表面官能团测定等手段对CAC进行表征,并用CAC吸附水中的4-氯苯酚(4-CP),2,4-二氯苯氧乙酸(2,4-D)和亮绿(LG)。试验条件下,吸附量达到:73.2、104、120 mg·g-1,实验结果证明CAC对水中有机污染物有很好的吸附效果。静态吸附实验主要研究了吸附剂用量、pH值、盐度、吸附时间、初始浓度和温度等因素对CAC吸附性能的影响,动态吸附实验主要研究了柱高、流速及吸附质初始浓度对CAC吸附性能的影响。对吸附等温线、动力学曲线及动态吸附穿透曲线进行模型拟合分析,结果显示如下:(1)CAC对4-CP吸附性能受pH影响较小。pH的增大不利于CAC吸附2,4-D与LG,均取最佳pH=2。盐度的变化对CAC吸附4-CP和2,4-D影响均不大,盐度的增大不利于CAC吸附LG。升温有利于4-CP和2,4-D的吸附,不利于LG的吸附。(2)Temkin模型可用于描述CAC对4-CP和2,4-D的吸附等温线,Koble-Corrigan模型可用于描述CAC对2,4-D和LG的吸附等温线。Elovich方程可以用来描述CAC吸附4-CP的动力学曲线,准二级动力学方程可用来描述CAC对2,4-D和LG的动力学曲线。推测吸附是非均匀表面的多分子层化学吸附过程。由热力学参数以及活化能计算结果可以看出,CAC对4-CP和2,4-D的吸附过程均是自发、吸热、熵增的过程,CAC对LG的吸附过程是自发、放热、熵减的过程,物理和化学吸附在三个过程中均有体现。(3)动态吸附实验表明,柱子越高、流速越慢、浓度越大越有利于吸附的进行。Yan模型可以很好的预测CAC对4-CP、2,4-D和LG动态吸附穿透曲线。解吸再生研究发现,乙醇溶液对CAC吸附4-CP和2,4-D都有具有很好的解吸再生效果。NaOH溶液对CAC吸附LG的解吸效果较好,HCl对CAC吸附LG的再生效果较好,吸附材料均可以重复利用。
[Abstract]:Waste biomass has environmental, social and economic benefits in the development and application of wastewater treatment. In this paper, activated carbon (CAC),) was prepared from walnut shell by ammonium oxalate-heating carbonization method, and the yield of activated carbon was 44.1%. CAC was characterized by isoelectric point, specific surface area of SEM,FT-IR, and surface functional group. 4-chlorophenol (4-CP), 2o 4-dichlorophenoxyacetic acid (4-CP) and bright green (LG). Were adsorbed by CAC. Under the experimental conditions, the adsorption capacity reached 73.2104120 mg g-1. The experimental results show that CAC has a good adsorption effect on organic pollutants in water. The static adsorption experiments mainly studied the effects of the amount of adsorbent, pH value, salinity, adsorption time, initial concentration and temperature on the adsorption performance of CAC. The effects of flow rate and initial concentration of adsorbate on the adsorption performance of CAC. The model fitting analysis of adsorption isotherm, kinetic curve and dynamic adsorption penetration curve is carried out. The results show that: (1) the adsorption properties of CAC to 4-CP are less affected by pH. The increase of pH is not conducive to the adsorption of 24-D and LG, by CAC. Average optimal pH=2. The change of salinity had little effect on the adsorption of 4-CP and 2n4-D by CAC, but the increase of salinity was not conducive to the adsorption of LG. by CAC. (2) the Temkin model can be used to describe the adsorption isotherms of CAC for 4-CP and 2O4-D. The Koble-Corrigan model can be used to describe the adsorption isotherms of CAC for 2C4-D and LG. The Elovich equation can be used to describe the kinetic curves of CAC adsorption 4-CP, and the quasi-second-order kinetic equation can be used to describe the CAC kinetic curves of 24-D and LG. It is inferred that the adsorption process of multimolecular layer chemisorption on heterogeneous surface. From the thermodynamic parameters and the calculated results of activation energy, it can be seen that the adsorption process of 4-CP and 24-D by CAC is spontaneous, endothermic and entropy increasing, and the adsorption process of LG by CAC is spontaneous, exothermic and entropy decreasing. (3) dynamic adsorption experiments show that the higher the column is, the slower the flow rate is, and the higher the concentration is, the more favorable the adsorption is. Yan model can be used to predict the effect of CAC on 4-CP. (2) dynamic adsorption and penetration curves of 4-D and LG. The results of desorption and regeneration showed that ethanol solution had good desorption and regeneration effect on CAC adsorption of 4-CP and 2o 4-D, NaOH solution had better desorption effect on CAC adsorption of LG and HCl on CAC adsorption of LG. Adsorption materials can be reused.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703;TQ424.1

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